The semiconductor integrated circuit (IC) industry has experienced rapid growth. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs. However, such scaling down has also been accompanied by increased complexity in design and manufacturing of devices incorporating these ICs, and, for these advances to be realized, similar developments in device design are needed.
Concurrent with advances in functional density, developments in microelectromechanical systems (MEMS) devices have led to entirely new devices and structures at sizes far below what was previously attainable. MEMS devices can be constructed to perform a variety of tasks including power generation, light projection, force sensing, switching, and locomotion. Forming such devices may involve techniques rarely seen in conventional circuit design that may incorporate multiple substrates and a variety of novel processes and materials. Here too, progress depends on continuing developments in device design and manufacturing.
As merely one example, some MEMS devices incorporate multiple substrates. Depending on how the substrates are bonded, the attachment points and attaching structures may impose strict design rules. While existing techniques for bonding substrates and forming structures incorporating multiple substrates have been generally adequate, they have not been entirely satisfactory in all regards.